Rotary wave compressors and the like



April 5, 1969 R. c. WEATHERSTON 3,438,569

ROTARY WAVE COMPRESSORS AND THE LIKE Filed Feb. 28, 1967 Sheet of 5mvsm'ox ROGER c. WEATHERSTON.

April 15, 1969 R. c. WEATHERSTON 3,433,559

ROTARY WAVE COMPRESSORS AND THE LIKE Sheet 18 of 5 Filed Feb. 28, 1967INVENTOR ROGER C. WEATHERSTON.

April 5 1969 R. c. WEATHERSTON 3,438,569

ROTARY WAVE COMPRESSORS AND THE LIKE Filed Feb. 28, 1967 Sheet 3 of sCYCLE TIME ABUTMENT OPENS AND DISCHARGE COLLECTION seems END -ABUTMENTABUTMENT CLOSED DISCHARGEJ (10353 FOR TO COLLECT? NEXT CYCLE b a g 3PISTON LEANES 3 CYLINDER PSTON PATH Z CHARGE STARTS FOR CHARGE NEXTCYCLE END PISTON ENTERS PlsToN NTERS CYLINDER FOR NEXT CYCLE INVENTORROGER C.WEATHERSTON April 1969 R. c. WEATHERSTON 3,438,569

ROTARY WAVE COMPRESSORS AND THE LIKE Filed Feb. 28, 1967 Sheet 4 of 5INVENTOR ROGER C WEATHER STON.

April 5, 1969 R. c. WEATHERSTON r 3,438,569

ROTARY WAVE COMPRESSORS AND THE LIKE Sheet Filed Feb. 28, 1967 INVENTORROGER C. WEATHERSTON.

United States Patent Int. 'Cl. F04c 17/18 US. Cl. 230-150 1 ClaimABSTRACT OF THE DISCLOSURE A fluid rotary compressor and/ or motor, oneor more pistons rotatable in one or more annular expansible chambers, arotary abutment member providing a closure and an escapement for thepiston or pistons, gears synchronizing piston movement with abutmentmovement and supply and exhaust passages in the cylinder walls and/ orthe abutment member.

CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of US. Ser. No. 572,600 filed Aug. 15, 1966 andassigned to the assignee of the present application.

BACKGROUND OF THE INVENTION The present invention relates to rotary waveexpansible chamber devices that function as fluid compressors and fluidexpanders or fluid motors. More specifically the present inventionrelates to such devices wherein the expansible chamber is characterizedby a continuously rotating working member and a rotating abutment membermoving in synchronization therewith.

Conventional positive displacement rotary devices, while having definiteadvantages over reciprocating compressors or motors, cannot compete on apower-to-size basis with axial flow compressors or turbines. The mainreason for this failure to compete is attributable to the inability ofpresent designs to efiiciently achieve sufliciently high piston orworking member displacement rates.

It is accordingly an object of the present invention to provide a rotaryexpansible chamber device that operates efficiently at sufliciently highenough displacement rates to compete favorably with axial flowcompressors on a power-to-size basis.

At the high displacement rates contemplated in one aspect of the presentapparatus compression and expansion are not accomplished by conventionalquasi steady state processes, but rather by nonsteady flow processescharacterized by compression (shock waves) and expansion fans.

It is therefore a further object of the present invention to provide arotary wave device that functions as a compressor or an expanderincorporating into its design, relationships that are dictated bynonsteady flow phenomena.

As is well known, gas turbines cannot utilize a high temperature workingfluid above about 1,500 F. In addition, axial flow compressors requiremany stages for eflicient high compression operation. Moreover, thesetypes of machinery are seriously limited in their utilization ofabrasive or corrosive fluids.

It is further an object of the present invention to provide an apparatusthat can operate at high displacement rates with high temperaturefluids.

A further object of the present invention is to provide an apparatusthat can operate at displacement rates in the range of axial flowcompressors and is capable of injecting relatively abrasive and/ orcorrosive fuels or working fluids.

A still further object of the present invention is to provide anapparatus that can operate at substantially the same displacement ratesof axial flow compressors Without requiring many stages for highcompression.

A further object of the present invention is to provide a rotary waveexpansible chamber device that does not require lubrication or directcontact sealing between the working members and its cylinders.

A still further object of the present invention is to provide a rotarywave expansible chamber device wherein a plurality of working members instacked relation are serviced by a single abutment member.

SUMMARY OF THE INVENTION Basically, the principles according to oneaspect of the present invention are achieved by providing means defininga generally annular cylinder, piston means rotatably mounted in saidcylinder, the cross-sectional area of said piston and that of saidannular cylinder being so related as to provide a finite clearance areabetween said piston and cylinder equal to a small percentage of thepiston area, an abutment means rotating in timed relation with saidpiston and means providing fluid communication with said cylinder, thearea of said last mentioned means being at least substantially equal tothe cross-sectional area of said cylinder.

In order to achieve the high displacement rates contemplated by thepresent invention, the fluid flow rates must be considerably higher thanthose of equivalent sized prior art devices. This is accomplished,according to the present invention, by providing for substantiallyunrestricted communication between the supply to and exhaust from thecylinder. In this manner, undesirable high flow losses or choking at theinlets or outlets, which would severely limit the mass rate of flow, isavoided. In addition, the piston or working members must be permitted tomove at very high speeds. Prior art devices have critical sealingrequirements between pistons and cylinders, utilizing piston rings orthe like. With such forms of direct contact sealing, friction betweenthe piston and cylinder forbids high operating speeds. This limitationis overcome according to the present invention by providing a small butdefinite clearance between the piston and cylinder. At the high pistonspeeds contemplated by the present invention, it has been found that theleakage rate is small and tolerable compared to the piston displacementrate. Moreover, the piston lubrication problem is eliminated. As isapparent, the high speeds are responsible for the desired highpower-to-weight ratios.

According to another aspect of the present invention, lower speedcompressor and/or expander action is permitted without the use ofsealing rings or the like. In addition, the overall size and bulk of thecompressor and/or expander is greatly reduced as compared toconventional reciprocating devices of similar displacement. Basicallythe foregoing advantages are realized by the provision of an annularcylinder, a piston having a broad helical face rotating in the cylinder,an abutment member rotating in timed relation with said piston locatedin a plane that is tangent to an outer wall of the annular cylinder atthe points where the piston exits therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of thepresent invention, reference should be had to the following detaileddescription of the same taken in conjunction with the accompanyingdrawings wherein:

FIGURE 1 is a pictorial schematic view of a single piston and cylinderassembly according to one aspect of the present invention with certainparts thereof broken away.

FIGURE 1A is a piston-cylinder section illustrating the clearances.

FIGURE 2 is an enlarged pictorial view of a portion of the structureshown in FIGURE 1.

FIGURE 3 is a pictorial schematic view of the assembly of FIGURE 1 froma different angle.

FIGURES 4-7 are schematic views illustrating the sequential operation ofthe device shown in FIGURE 1.

FIGURE 8 is an idealized wave diagram of piston displacement versustime, for a compression process of the device illustrated in FIGURE 1.

FIGURES 9A9C are schematic views illustrating the advantages of apreferred piston shape.

FIGURE 10 is a plan view of a modification of the device shown in FIGURE1 with parts thereof broken away.

FIGURE 11 is a pictorial view of the drum and piston assembly shown inFIGURE 10.

FIGURE 12 is a pictorial view of a second modification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawingsand more particularly to FIGURES 1-3, the basic cylinder-piston andabutment assembly is indicated generally by the numeral 10 and is shown(FIGURE 3) as comprising a working member unit 20, a cylinder unit 30and an abutment unit 40.

The unit comprises a cylindrical hub 21 that is fixedly mounted on asolid shaft 22. As is common, shaft 22 is rotatably mounted on suitablebearings (not shown). The outer peripheral surface 23 of hub 21 hasprojecting radially outwardly therefrom a piston or working member 24having a top edge 25 and side edges 26. As shown piston 24 isrectangular in shape, although any other suitable shape would suffice.

The cylinder unit comprises a generally annular inverted U-shapedchannel 31 having an outer peripheral wall 32, two side walls 33 andbottom edge surfaces 34. The channel is discontinuous defining twospaced open end faces 35 and 36 as shown spaced about 90 apart. Channel31 is mounted on any suitable stationary means 80 in surroundingrelation to the hub 21 and piston 24. The dimensions of the piston, huband channel are so chosen that a definite clearance space existstherebetween. Thus, numeral 37 depicts the clearance between piston sideedges 26 and channel side walls 33, numeral 38 depicts the clearancebetween piston top edge 25 and channel outer wall 32 and numeral 39depicts the clearance between channel bottom surfaces 34 and hubperipheral surface 23. It has been found that clearance areas rangingfrom 0.3 to 3.0 percent of the piston area provide the requisitefrictionless, lubricationless freedom of motion between the piston andchannel; such freedom being necessary to permit very high speeds ofoperation, and yet keep the leakage to a tolerable level. The leakagesource from clearance 39 is usually larger than the piston leakagesources from clearances 37 and 38; however, at the high piston speedsthe total leakage (piston plus channel and hub) can be tolerated.Although shown here as an inverted U, the channel 31 could take anotherconvenient and suitable shape without departing from the spirit of theinvention.

The abutment unit 40 includes a generally frusto conically shapedabutment member 41 having conical top and bottom surfaces 42 and aperipheral side edge 43 which may be, for example, cylindrical; althoughother suitable shapes would suffice. Side edge 43 is interrupted by acutaway escapement section 44 defined by a pair of radially inwardlyextending surfaces 45 meeting a generally arcuate surface 46. The depthof surfaces 45 is dependent upon the height of piston 24, as will becomeapparent. The bottom surface 42 is undercut to define an annular flatlip 420 (FIGURE 3). The bottom surface 42 also contains an opening 47and communicating therewith is a wedge-shaped internal flow passage 48that leads to an arcuate opening 49 on the peripheral side edge 43. Aswill become apparent hereinbelow, opening 49 funct-ions as either acollection or discharge nozzle dependent upon whether the improveddevice is functioning as a fluid compressor or fluid motor. A tubularshaft 50 having an internal passage 51 is fixedly and sealingly attachedto abutment member 41 with passage 51 in fluid communication with flowpassage 48 through opening 47. Shaft 50 is mounted for rotation inconvetnional bearings (not shown). The axis of rotation, Y, of shaft 50is substantially perpendicular to the axis of rotation, X, of shaft 22and the distance therebetween is so chosen that arcuate opening 49 aswell as edge 43 as it sweeps past channel end face 35 is spacedtherefrom just enough to prevent rubbing contact therebetween. Inaddition, the lip 420 is spaced with a small clearance from hubperiphery 23 to provide a substantial seal thereat (see FIG- URE 4).

The height of opening 49 is substantially equal to the height of channelend face 35 such that as opening 49 sweeps by end face 35, the flow fromone to the other is unrestricted. The arcuate length of opening 49 isgreater than the width of channel end face 35 thereby taking intoconsideration that it takes finite time for the total crosssectionalarea of the channel and face to be exposed. It is therefore apparentthat the actual arcuate extent of opening 49 will depend, inter alia,upon the speed of abutment member 41. It is to be noted that channel endface 36 is freely exposed to the atmosphere so that flow thereto ortherefrom is always unrestricted. Alternately, if some fluid other thanair is utilized, a plenum chamber or reservoir could provide theunrestricted communication.

A cylindrical sealing band 52 at least equal in height to the height ofopening 49 is attached at ends 53, 54 to side walls 33 of channel 31 andsurrounds the entire edge surface 43 of abutment member 41. Band 52functions to seal the passage 48 from the environment when not incommunication with channel end face 35.

Suitable timing gears and 61 are fixed respectively to shaft 22 andshaft 50 to synchronize the movement of one with respect to the other. Apair of bevel gears 62 and 63 may be provided in engagement with gears60 and 61 to transmit the motion, as is conventional.

The foregoing description has characterized the basic rotary expansiblechamber device according to one aspect of the present invention. Theembodiment to be described next below depicts certain refinements asapplied to this basic device to increase its operating efiiciency.However, before discussing this modification, the operation of the basicassembly will be described with reference to FIG- URES 18.

Assuming the rotary expansible chamber device 10 is to function as afluid compressor, shaft 22 will be driven by suitable high speed motormeans (not shown) in the direction of arrow A. This rotation producesrotation of abutment member 41 in the direction of arrow B. As isobvious, the piston and abutment are geared together such that theescapement cutaway just reaches the channel end face 35 as the pistonjust leaves the channel or cylinder.

The finite clearances existing between the moving and stationaryelements as described supra permit the former to be rotated at very highspeeds. Piston speeds of substantially 250-500 feet per second, forexample, are possible; this is to be contrasted with speeds of 25-50feet per second of conventional rotary abutment-type expansible chamberdevices. The ratio of piston speed to the initial speed of sound of thefluid being compressed is referred to as piston Mach number. At pistonMach numbers of from, say, 0.2 to 0.5 (equivalent to piston speeds offrom 250-500 feet per second), the process of compression is notrepresented by homogeneous conditions of pressure and temperature thatvary as a function of time or piston position within the cylinder.Rather, compression is accomplished by nonsteady flow processes whereinonly a few discrete pressure levels exist for a finite time within thecylinder. It is therefore necessary to synchronize the movements of thepiston and the abutment on the basis of a nonsteady flow phenomenonrather than on the basis of quasi-steady flow phenomenon as experiencedin conventional slow velocity rotary piston designs.

With the foregoing in mind, a discussion of the operation will nowproceed. For an initial point of operation, it is assumed that adischarge of high pressure gas from channel end face 35 to collectornozzle opening 49 has been completed and that cutaway escapement portion44 is in line with end face 35 as shown in FIGURES 4 and 4A. The piston24 has just left the channel end face 35 and is in the escapementportion. The piston is continuously drawing in a fresh charge of fluidat initial conditions from the atmosphere through end face 36 forsucceeding cycles. Since the total channel cross-sectional area is fullyexposed at end face 36, the charge enters without restriction at thepiston Mach number. This is depicted at region a in FIGURE 8. The nextstep of significance is the closing of end face 35 by the side edge 43of abutment 41 as shown in FIGURES 5 and 5A. It is to be noted that thepiston has not yet passed through end face 36 to thereby reenter thechannel. The closing of end face 35, depicted at b in FIGURE 8, resultsin a hammer shock wave being created of such strength that it brings theflow to rest inside of the channel thereby increasing its pressure. Thepath of the shock wave is indicated at 1 in FIGURE 8. The piston shouldreenter end face 36 at or before the time the shock wave arrives thereat(depicted at c in FIGURE 8). In this manner a precompression orsupercharging of the incoming fluid is accomplished. When the pistonreenters the channel, a series of shock waves (2 through 6 in FIGURE 8)go back and forth between the piston and the abutment side edge 43 untilsuch time as the desired pressure level is established by the arrival ofthe last shock wave at the end face 35 (depicted at point d in FIGURE8). As is known, these shock waves are produced by the action of thepiston and the abutment alternately causing the fluid to be acceleratedto the piston Mach number and to be stopped at the abutment end. At thetime when the last shock arrives at the abutment side edge 43, theopening 49 of collection nozzle 48 just begins to uncover the channelend face 35 to receive the compressed fluid. This is also depicted at din FIGURE 8.

Although the piston 24 is shown as having a fiat radial front face, atapered face would provide for more efficient collection. This isillustrated in FIGURES 9A, 9B, and 90 wherein the piston 240 is shown ashaving a front face 241 tapering outwardly from the inner wall 333 tothe outer wall 334 of channel 330. FIGURES 9A9C shows the transitionfrom collection to escapement. It can be seen in FIGURE 9A that at thestart of escapement with the abutment rotating in direction C, a volume,V, of high pressure fluid still remains in channel 330. If the pistonface were radial, the volume, V, would be doubled and most of the fluidtherein would be lost in the escapement portion 440 and in addition aleakage path would be opened from collector 490 to escapement portion440, thereby markedly reducing efiiciency. As shown, the tapered facemaintains a seal at S and also allows substantially the total volume inspace, V, to pass into the collector.

The seal afforded by band 52 prevents the collected gas in passage 48from being discharged wastefully. The collected high pressure gas thenflows through passage 50 for suitable utilization.

It thus can be seen that there are three critical timing relationshipsbetween the piston, channel and abutment, to wit: (1) arrival ofabutment escapement portion at the channel end face 35 as piston leavesthe end face; (2) arrival of piston 24 at channel end face 36 at orbefore the shock wave, due to abutment closing face 35, arrives thereat;and (3) arrival of opening 49 at channel face 35 as the last of thechosen number of shock waves (dependent upon desired pressure ratio)arrives thereat.

As stated earlier the first relationship is achieved by proper choice ofgears 60, 61, 62, and 63. Since the second relationship depends upon thetime it takes for a shock wave to travel the length of the channel, itis only necessary to adjust the length of the channel as by bringing endface 36 closer or further away from end face 35. The third relationshipis achieved by adjusting the arcuate extent of collection nozzle opening49 such that collection starts at the proper time.

As is apparent, the latter two relationships are dictated by thenonsteady compression processes which take place as a result of the highpiston speeds. The consequences of not taking into account thesenonsteady flow processes appear as losses which reduce overallefliciency. For example, if the piston does not enter channel face 36 ator before the arrival thereat of the shock wave, some of the intialpressure build-up in the channel, before piston action, will bedissipated. Thus the effect of supercharging will be diminished. Also,if the collection starts after the arrival of the last shock at end face35, the fluid in the channel will be over-compressed and higher than thepressure in collector nozzle 49. Adjustment to the nozzle pressure wouldultimately take place by undesirable dissipative throttling processes.

The finite clearances bet-ween the moving and stationary elements,enabling high piston Mach numbers, are sources of leakage, but at suchhigh piston speeds the ratio of the leakage rate to the pistondisplacement rate is relatively small and tolerable.

One embodiment for obtaining higher ratios of piston displacement ratesto leakage loss rates is shown in FIG- URES 10 and 11. In these figures,like numerals refer to like parts with the exception of primes. Thearrangement shown in FIGURES l0 and 11 comprise many cylinder unitscombined to form a stacked assembly that is serviced by a singleabutment unit depicted generally at 40'. For ease in assembly, themulti-cylinder units comprise an elongated generally cylindrical member31 that is discontinuous defining an upper end face and a spaced lowerend face 36'. Member 31 is closed by side edges 33' and face 35arcuately extends therebetween defining a circular surface thatcomplements the circular surface of abutment side edge 43'. Interiorlyof member 31 are a plurality of cylinder defining partitions or fingers34, each extending from end face 35 to end face 36' intermediate sideedges 33'. The fingers 34' extend inwardly fro-m the peripheral surface32' of cylinder member 31' and terminate adjacent a drum or hub 23'. Asshown the drum is not cylindrical, but is more hyperboloid in shape. Thehyperboloid shape is necessary in order to maintain the substantialfluid seal between abutment lip 420 (see FIGURE 3) and the drumperipheral surface 23. To maintain such a seal, the annular lip 420 thatnearly touches the drum surface 23 must do so in substantially a commonplane perpendicular to the abutment axis. The abutment lip 420 nearlycontacts the center cylinder on the drum centerline parallel to theabutment axis but for the outer cylinders the contact is off thecenterline in a direction toward the axis of the abutment. Toaccommodate the off centerline condition and yet maintain a common planeof abutment-drum contact, it is necessary to increase the drum radii ofthe outer cylinders.

A plurality of pistons 24' extend generally radially outwardly from drum23' and fit between each partition 34; however, the front face elementsof the pistons of the outer cylinders are not quite radial but at slightangle with respect to the drum radius. This is necessary so that theentire piston face will be parallel to the abutment face as it leavesits channel or cylinder. As is apparent, cylindrical member 31' must besplit for receiving drum 23'. As shown, each successive piston ismounted at a slightly different angular position consistent with thetiming requirements that each piston follow closely behind the terminuswhich separates the trailing edge of the opening 49 from the beginningof the escapement as each piston rotates in succession past eachchannel. The clearances between the elements are similar to that aspreviously described.

In addition, although not clearly illustrated, it is obvious that endface 36' will not be planar as in the single piston embodimentpreviously described; but, instead, will be curved from each end 33'toward the central cylinder. It is clear that some such shaping isnecessitated by the requirement that the effective length of thecompression or expansion process in each cylinder section be the same,and since the end face 35' is not planar, but curved as shown, the otherend face 36' must also be curved to satisfy the above requirement.

The abutment unit 40 is similar to abutment 40 previously described withthe exception that escapement portion 44' may be larger to accommodatethe staggered pistons.

Each piston-cylinder unit operates with respect to the abutment memberand collection nozzle 49 in the same manner as the single unit describedabove. The predominate leakage loss from clearance 39 as mentioned forthe single cylinder case is markedly reduced in the instant stackedembodiment. This is true, since, now it is only the outer portions ofthe outer two channels which communicate with the atmosphere thatexperience this loss. There may be some drift from one channel toanother intermediate the outer two, but fluid leaving one channel mustreappear in another channel. This drift, therefore, does not constitutea loss to the outside environment. Thus, the channel and drum leakageloss to the atmos phere from the outer two cylinders is similar to thesingle unit previously described; however, since the displacement rateis now multiplied by a factor equal to the number of pistons, the ratioof leakage rate to displacement rate is greatly reduced. In addition,the leakage are through sealing band 52' from collector nozzle 49' isgreatly reduced since the are through which collection takes place isgreatly increased.

An additional stacked piston-cylinder unit may be located inhorizontally opposed relation to unit and this is depicted at 319 inFIGURE 9.

The embodiment shown in FIGURE 12 utilizes a single piston membersimilar to the FIGURE 1 embodiment combined with a large cylinder volumesimilar to the FIG- URE 11 embodiment. In FIGURE 12 parts similar tothose already described are depicted by the same numerals with doubleprimes.

The cylinder unit 30" comprises an annular inverted U-shaped channel 31having an outer peripheral wall 32-", two side walls 33" and bottom edgesurfaces 34". The channel is discontinuous defining two spaced open endfaces, only one of which is shown at 35". The other end face is similarto face 36 of FIGURE 2.

Rotatably mounted interiorly of channel 31 is a drum 23" that is similarto the one shown in FIGURE 11. A suitable support member 80" provides amount for the drum. The drum 23 contains a piston land 25" that issubstantially helically wrapped about the peripheral surface thereof. Asshown the exact curvature of piston 25" is such that a front face 24"thereof nearly touches the joinder of escapement portion 45" andabutment side edge 43" as the piston passes through the escapementcutaway 44".

The dimensions of the piston land, drum and channel may be such as toprovide finite clearances that are similar to those provided for in theprevious embodiments.

An abutment unit 40" includes a planar abutment member having top andbottom surfaces 42" and a peripheral side edge 43". Side edge 43" isinterrupted by a cutaway escapement section 44" defined by a pair ofradially inwardly extending surfaces 45" meeting a generally arcuate 46"as in the FIGURE 10 embodiment. Suitable gearing (not shown) may beprovided to synchronize the rotation of the abutment member in thedirection of arrow B" with the rotation of the drum in the direction ofarrow A".

Instead of having passages in the abutment member as in the previousembodiments, one or more passages or ports may be provided in a sidewall33" of the annular cylinder as shown at 49". Alternatively, one or moreports might be provided in the outer wall 32". In which case, a suitablevalving mechanism could be aflixed to the abutment. As before, this port49" will function either as a high pressure outlet in the case ofcompressor action or a high pressure inlet in the case of expander orfluid motor operation; the fluid being delivered or received by means ofsuitable passages (not illustrated).

The sealing hands 52 or 52 of the previous embodiments are not requiredin the instant embodiment, since there are no flow passages in theabutment member to be sealed. However, if it were desirable to utilize aflow passage in the abutment, then suitable sealing bands would beprovided.

The operation of the FIGURE 12 embodiment is similar to that for theembodiments previously described except that the piston land, having amuch broader face than the piston 24 of FIGURE 2, for the same overalldimensions, functions to displace a greater volume of fluid with lessthan a proportionate increase in the leakage area. In other words, theratio of displacement to leakage is greater. In addition the piston canoperate at lower speeds, say, from about 50 to 100 feet per second ascompared to 250500 feet per second of the FIGURE 10 embodiment. Withthese lower speeds, choking at the port 49 is alleviated; therefore, arelatively smaller port as shown can be utilized.

It is to be noted that abutment member 40", as well as 4-1 and 40' ofthe previous embodiment, lies in a plane that is tangent to the cylinderouter wall 32" at the point where the piston land 24" exits therefrom.With this arrangement an extremely broad piston face can be accommodatedto provide a compact assembly.

Other modifications without departing from the spirit of the presentinvention are possible. For example, the abutment plate may be replacedby two endless :belts; one to provide for piston escapement and theother to provide for collection, in the case of compressor operation orto provide for supply in the case of fluid motor operation. The abutmentbelt would contain a plurality of slotted portions to allow successivepistons to pass through and would rotate about an end face similar to35' in FIGURE 10. The second belt containing a plurality of portopenings would operate in a plane at relative to the first and wouldserve to communicate each cylinder with a collection plenum chamber inthe case of compressor operation.

Although the foregoing discussions have assumed that the device operatesas fluid compressor, it is obvious that the identical structure willserve equally as well when operating as a fluid motor or expander. Inwhich case, the piston or pistons would be driven by high pressureand/or high temperature working fluid. Since it is only necessary tocool single piston elements rather than myriad turbine blades, it isclear with the present device that higher temperature fluids can behandled.

Moreover, the finite clearances between the elements in addition tosatisfying the high speed requirements permit the use of relativelyabrasive or corrosive fluids in that absolute sealing is not essential.

Other modifications will suggest themselves to those skilled in the art;therefore, it is intended that the present invention should be limitedonly by the scope of the appended claim.

I claim:

1. A device of the character described, comprising;

(a) a first generally annular cylinder having two side walls and anouter wall, said first cylinder being discontinuous defining a firstpair of spaced end faces,

(b) a second generally annular cylinder spaced from and parallel withsaid first cylinder having two side walls and an outer wall, said secondcylinder being discontinuous defining a second pair of spaced end faces,

(c) a first drum rotatable within inner surfaces of said side walls ofsaid first cylinder, having a helical piston thereon rotating betweensaid side walls of said first cylinder and passing through said firstpair of spaced end faces,

(d) a second drum'rotatable within inner surfaces of said side walls ofsaid second cylinder, having a helical piston thereon' rotating betweensaid side walls of said second cylinder and passing through said secondpair of spaced end faces,

(e) one end face of each of said first and second pair of end facesbeing located in the same plane and having a cylindrical contour,

(f) a single cylindrical abutment member rotating in timed relation withsaid drums and located between the cylindrical contours of each of saidone end faces,

(g) a single cutaway escapement portion on said abutment member forsequentially receiving the helical pistons of each of said drums as theypass through their respective said one end face, and

(h) said drums and said abutment being so mounted that a close spaced,no-contact relationship is maintained therebetween.

References Cited UNITED STATES PATENTS Re. 918 2/1860 Roots 103-l25188,108 3/1877 Disston 230-150 1,352,237 9/ 1920 Andrews et a1 1031251,619,514 3/1927 Holman 103--125 1,785,140 12/1930 Morris 103-1251,946,097 2/1934 Morris et a1. 103125 2,010,797 8/1935 Archbold et a1.9l--85 3,182,600 5/ 1965 Guinard 103-125 DONLEY I STOCKING, PrimaryExaminer.

WILBUR I. GOODLIN, Assistant Examiner.

